EIGRP is based on the concept of diffusing computations. When something changes in network topology, the routers that detect a loss of network prefix will send out EIGRP QUERY messages that propagate in circular waves similar to the ripples on water surface. Every queried router will in turn query its neighbors and so on, until all routers that knew about the prefix affected. After this, the expanding circle will start collapsing back with EIGRP REPLY messages. The maximum radius of that circle...
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